Printing apparatus with type wheel disconnected from selection means during return to home position



March 7, 1967 E, HICKERSON 3,307,676

. PRINTING APPARATUS WITH TYPE WHEEL DISCONNECTED FROM SELECTION MEANS DURING RETURN TO HOME-POSITION Filed Dec 30, 1965 I 2 Sheets-Sheet 1 INVENTOR JOHN E. HICKERSON March 7, 1967 J. E. HICKERSON 6 PRINTING APPARATUS WITH TYPE WHEEL DISCONNECTED FROM SELECTION MEANS DURING RETURN TO HOME POSITION 2 Sheets-Sheet 2 Filed Dec. 50, 1965 llnzull Q 5 1 PM )4;

n FEG. CYCLE1 CYCLE2 CYCLE3 RESTORE V RESTORE RESTORE PRINT PRINT PRINT sEuicnohx JELECTION SELECTIOm E IQN H MP LL r1 AQTUALQR lows h liE ADjOI/UION v HE DWVEBIIQAL. ERINLHAMMEWR r my 19 so RE TQBLSRR ON Y /L L 3,367,676 Patented Mar. 7, 1967 3,307,676 PRINTHNG APPARATUS WITH TYPE WHEEL DES- CONNEQZTED FRQM SELECTION MEANS DUR- IN G RETURN TO HOME POSITION John E. Hickerson, Lexington, Ky., assignor to International Business Machines Corporation, Armonk, N.Y., a corporation of New York Filed Dec. 30, 1965, Ser. No. 517,564 8 Claims. (Cl. 197-48) This invention relates to printing mechanisms and more particularly to mechanisms of this nature having provision for progressive selection generally in a preferred direction and improved restoring action.

One form of prior mechanism comprises a printing wheel or cylindrical printhead and associated selected mechanisms that are actuated in order to select characters for printing. The selection occurs in response to selective movement of intricate keyboard mechanisms, or in response to data signals actuating electromagnetically responsive mechanisms. The philosophy of operation of such printing devices has usually been predicated upon cyclical operation wherein a first portion of each cycle is taken for printing selection and a comparable later portion of each cycle is required for restoration of the printing element and the selection mechanisms. Improvements have been made in various components and their operation so that higher speeds of operation are now possible. However, efforts have been hindered to some extent, due to the time required for selection and restoration in successive cycles of operation of the mechanisms.

Accordingly, an object of the present invention is to provide printing apparatus that is capable of higher speeds of operation.

Another object of the invention is to provide printing apparatus with improved selection and restoration features.

An additional object of the invention is to provide selection mechanism that is useful in connection with single element printing devices, either of the printwheel variety or the cylindrical matrix variety.

Still another object of the invention is to provide a compact printing apparatus with low mass, thereby lending itself to improved selection and restoring principles of operation.

A further object of the invention is to provide printing apparatus with improved selection and restoring features that is operable under mechanical or electrical control or combinations thereof.

Still another object of the invention is to provide printing apparatus that is operable in a continuous or intermittent cyclical manner.

Also, an object of the invention is to provide apparatus in which the selection and response restoring principles are applicable over a wide range of operating movements of the apparatus.

In order to accomplish these and other objects of the invention, printing mechanism is arranged with a portion for selecting characters that is selectively actuatable prior to printing to position a particular character for printing, that is, continually and progressively movable in a predetermined direction; that is disconnected from the printing element for restoration of the printing element following printing in each cycle, and that'has a configuration that permits continuous selection and disconnection from the printing element without the necessity for restoring the selection portion. In an alternative arrangement, the selection and restoration principles are applied to both vertical and rotary selection movements of a matrix printing element. The mechanisms disclosed are indicated as being operable under electrical and/ or mechanical control or combinations thereof. In addition, the apparatus is indicated as being operable in a synchronous and continuous cyclical fashion or in an intermittent cyclical fashion, as preferred.

In another arrangement of the selection portion of the apparatus, selection output is derived from various combinations or selection inputs that are represented by move ments of selecting elements in a number of selecting directions. The net selecting output, which may, for example, represent movements of selecting elements in both positive and negative directions, is still predicated upon progressive selection in a predetermined manner with elimination of the selection mechanism restoring action.

In still another version of the invention, the progressive selection principles and the mechanisms disclosed are combined with other types of selecting mechanisms based on full restoration, partial restoration, or non-restoration principles.

The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of the various embodiments of the invention as illustrated in the accompanying drawings.

In the drawings:

FIG. 1 represents printing apparatus including a print wheel and selection mechanism operable in a progressive manner with essentially a non-restoring action.

FIG. 2 is a perspective view showing the top portion of the print wheel in the apparatus of FIG. 1.

FIG. 3 is an alternative arrangement combining aspects of the print wheel version of FIG. 1 or a matrix printing cylinder with selection in rotary and vertical directions.

FIG. 4 illustrates the basic progressive selection principles involved.

FIG. 5 represents alternative selecting elements for use in the embodiments of FIGS. 1 and 3 with both positive and negative selection movements being elfected concurrently in order toderive a net selecting output to the printing element.

FIG. 6 is a chart illustrating typical mechanical actions involved in selecting and restoring the printing mechanisms during three typical cycles of operation.

The printing apparatus in FIG. 1 includes members indicated at 1 for eifectin'g printing, selection members at 2, restoring members at 3, and a data source and control block 4. The various printing members 1, 2, and 3 are generally concentrically mounted on a shaft 5. FIG. 1 is an exploded view of the various printing members in the first embodiment disclosed herein, arranged in this manner for greater clarity. The printing apparatus of FIG. 1 would normally take the more comp-act form shown in FIG. 3.

The members for effecting printing include a print wheel 6 having embossed or raised characters positioned at predetermined regular intervals around its periphery. Print wheel 6 is rotated to position a desired character for printing opposite a plunger 8 of a solenoid 9. The selection of characters on print wheel 6 during successive cycles of operation of the apparatus is under control of the selection elements 2 that are in turn selectively positioned under control of character representing pulses -derived from data source 4. The printing apparatus of FIG. 1 is generally maintained in the vertical position shown throughout the selection and printing of characters, and during subsequent restoration, with the various printing members being rotated as required about shaft 5.

Actual printing of a character on a media such as paper It) occurs by rear-strike action with plunger 8 being propelled at printing time toward paper 10 by the energization of solenoid 9. Plunger 8 strikes the rear of paper 10, presses paper 10 against print wheel 6 and printing is effected by ribbon 11. The energization of wheel 6 two increments from home position.

solenoid 9 occurs at the proper time during each printing cycle by an impulse on line 13 from the data source and control block 4.

.For purposesof illustration, print wheel 6 is assumed to have eight characters that are selected for printing under control of the selection element 2. The eight characters are mathematical symbols shown more clearly in FIG. 2. The home position of print wheel 6 is indicated by arrow 14 associated with plunger 8, FIG. 2. If print wheel 6 is maintained in the home position, the mathematical symbol plus is selected for subsequent printing by actuation of plunger 8. Print wheel 6 is movable to seven other discrete positions for printing one of seven other mathematical symbols shown in FIG. 2. p

The selection portion 2 of the printing apparatus in FIG. 1 includes planetary gear elements that are rotated predetermined weighted amounts by l, 2, and 4 coded impulses directed on lines 15, 16, and 17 to energize select-or magnets 18, 19, and 20 in a selective manner and according to the coded permutation of the character required for printing.

The selection portion of the printing apparatus in FIG. 1 includes actuator discs 22, 23, and 24 that impart l, 2, and 4 amounts of movement, when selected, to an output ratchet 25, with the extent of movement of ratchet 25 representing the aggregate extent of movements of the actuator discs 22, 23, and 24. Output ratchet 25 is connected by means of a pawl 26 and in association with a restoring ratchet 27 for effecting rotation of print wheel 6.

Each of the actuator discs 22, 23, and 24 has a predetermined number of ratchet teeth about its periphery, the number of teeth being the same for each actuator disc. However, due to the planetary gear configuration, each actuator disc 22, 23, and 24 imparts a weighted amount of movement to output ratchet 25, depending upon its position in the planetary gear train. A one tooth movementof actuator disc 22 imparts a one tooth movement of output ratchet 25. A one tooth movement of actuator disc 23 imparts a two tooth movement of output ratchet 25, while a one tooth movement of actuator disc 24 imparts a four tooth movement of output ratchet 25.

As indicated in FIG. 2, the eight character positions on print wheel 6 are represented by designations t 1, 2, 3, 4, 5, 6, and 7, respectively. The mathematical symbol plus is at home position and since no movement of print wheel 6 is required, no movement of actuator 22, 23, or 24 is necessary. For the other mathematical symbols, actuator discs 22, 23, and 24 are moved selectivcely to provide a combined aggregate movement to output ratchet 25 that corresponds to the relative numerical position of each individual character with respect to home position. To select the minus sign, designated 1 in FIG. 2, the l magnet 18-actuator disc 22 combination is actuated. A one tooth movement of actuator disc 22 therefore moves output ratchet 25 one increment to position the minus sign for printing.

The selection of the next character for printing, that is, the equal sign is effected by actuation of the magnet 19-actuator disc 23 combination to rotate print As another example, selection of the ratio symbol (1) occurs when the magnet 19-actuator disc 23 combination cor responding to two units of rotation of print wheel 6 and the magnet 2tl-actuator disc 24 combination, corresponding to four units of rotation of print wheel 6 are actuated concurrently. This produces an aggregate combined rotation of output ratchet 25 and print wheel 6 of six units from the home position. The selection of other characters for printing occurs in a comparable manner.

Rotation of print wheel 6 for eifecting selection of a plurality of characters greater in number than the eight characters selected for illustration is possible by adding additional selector elements, including additional selector magnets and actuator discs. By appropriate mechanical interconnection, for example, an additional magneoactuator disc combination could provide eight units of rotation of output ratchet 25 and thereby, in combination with the actuator discs 22, 23, and 24, provide for the selection of sixteen characters.

A description of the selector portion 2 of the printing apparatus will clarify the planetary actions involved. Arranged to the left of the printing mechanism is a shaft 2? that mounts a number of cam elements 3135 arranged for cooperation with a number of drive pawls iii-44. Shaft 29 may be driven by any suitable means collectively represented by a drive block 38. Drive block 38 may include a clutch member controlled by signals on line 36 to drive shaft29 continuously and in synchronism with data signals supplied on lines 15, 16 and 17 from data source 4, or drive block 38 may be controlled to drive shaft 29 intermittently under concontrol of impulses on line 36 in the case where data source 4 represents a keyboard, for example.

Drive paw ls 41, 42, and 43 are positioned for driving engagement with the teeth of actuator discs 24, 23, and 22 respectively. Drive pawl 41) is positioned for driving engagement with the restore disc 27. Normally, the drive pawls 40, 41, 42, and 43 are oscillated in close proximity to their associated discs, but not in engagement. Engagement of the drive pawls 40, 41, 42, and 43 is controlled by actuator elements 51, 52, 53, and 54 that are mounted on a shaft 55. During rotation of drive shaft 29 and reciprocation of pawils 4e, 41, 42, and 43, selector magnets 18, 19, and 20, and restore magnet 45 are energized selectively to connect pawls 40, 41, 42 and 43 to their respective discs. Energizetion of magnet 18, as shown in FIG. 1, rotates actuator member 54 in a clockwise direction. Extension 54a thereupon presses against drive pawl 43 and moves it into engagement with actuator disc 22. The reciprocation of drive pawl 43 by cam 34 as shaft 29 rotates thereupon drives actuator disc 22 the desired increment of movement, which as illustrated is one tooth of actuator disc 22. Cam 35 and drive pawl 44 are shown to illustrate the possibility of alternate driving and restoring of pawls for doubling the speed of selection. With cams 34 and 35 arranged on shaft 29 as indicated, actuator disc 22 can be driven by movement of drive pawl 43, that is, to the left in FIG. 1, while drive pawl 44 is restoring to the right. Subsequently, as drive pawl 44- is driven to the left to operate actuator disc 22, drive pawl 43 can be restoring to the right. The alternate driving and restoring of pawls 43 and 44 speeds up the selection operation.

The cut teeth on actuator disc 24 is in the same direction as the teeth on actuator disc 23. The teeth on actuat-or disc 22, on the other hand, are cut in an opposite fashion. Therefore, drive pawls 41 and 42 associated with actuator discs 23 and 24 are engaged from the opposite direction to drive discs 23 and 24 concurrently with driving of actuator disc 22 by appropriate arrangement of cams 32 and 33 on shaft 29. Drive pawl 43 could be arranged on the reverse side for driving engagement of actuator disc 22 as shown at 43a, rather than as illustrated.

Actuator disc 22 mounts a pinion gear 58 that is engaged with an internal gear 59 associated with actuator disc 23. Pinion gear 58 is also engaged with a spur gear 60 that is secured to a support disc 61 by a bearing sleeve 62. Sleeve 62 is broken away at 62a and 62b for convenience in illustration. Support disc 61 supports another pinion gear 63 that is engaged with an internal gear 64 mounted on the undersurface of actuator disc 24. Pinion gear 63 also engages another spur gear 65 that is secured to shaft 5. Output ratchet 25 is also secured to shaft 5 and is driven by rotation of spur gear 65.

With the planetary intenconnections arranged as just selector portion of the printing mechanism.

described, and with the proper selection of gear ratios, the weighted driving inputs to the planetary gear train are established as previously discussed. Thus, movement of actuator disc 22, one tooth by driving engagement with drive pawl 43 effects a one tooth rotation of output ratchet 25. Driving movement of actuator disc 23 one tooth -by engagement with drive pawl 42 rotates output ratchet two teeth, and a one tooth movement of actuator disc 24 resulting from driving engagement of drive pawl 41 causes a four tooth rotation of output ratchet 25.

Print wheel 6 has an associated coil spring 7 for restoring purposes. Coil spring 7 is grounded to frame as indicated at 12 at one end and attached to print wheel 6 by a hub connection indicated at 21 in FIG. 2. When a character other than the one at home position is selected for printing, print wheel 6 is moved in a direction indicated by arrow 30. During the process of rotation of print wheel 6 during selection, coil spring 7 is wound tighter and stores energy for subsequent restoration of print wheel 6 following printing An advantage offered by the planetary gear arrangement of the selector portion 2' of the printing apparatus in FIG. 1 is that selection of characters can be effected in a progresive manner without the necessity of restoring the primary selector elements involved. Therefore, according to a primary principle of the present invention the selector elements are moved preferably either intermittently or continuously in a predetermined direction and are not required to be restored to a home position as is conventional in printing mechanisms of this nature. The actuator discs 22, 23, and 24 are provided with ratchet teeth around their entire peripheries and movement of actuator discs 22, 23, and 24 is effected by driving engagement of the pawls 41, 42, and 43 with any tooth positioned in proximity to the driving pawls. Regardless of the number of printing cycles or the extent of selecting movements required by actuator discs 22, 23, and 24, these discs are moved continually and progressively in predetermined directions as indicated by the arrows 68, 69, and 70, respectively, FIG. 1.

Three typical cycles of operation are illustrated in FIG. 6. During the selection portion of each cycle, selection impulses are directed selectively on lines 15, 16, and 17, FIG. 1, to energize magnets 18, 19, and 20. Actuator discs 22, 23, and 24 are moved, or not moved, depending upon which of the magnets 18, 19, or 20 is energized. The selection impulses and movement of the actuator cams is depicted in FIG. 6. Following the selection portion of each cycle, print hammer 8 is actuated by energizing solenoid 9 as indicated at 78, 79, and 81), FIG. 6.

During the selection portion of each cycle, restore spring 7 is wound tighter. Following the printing action, print wheel 6 is released from the selection portion of the printing apparatus and returned to home position by stored energy from spring 7. The release of print wheel 6 for subsequent restoration is performed by the restoring portion of the printing mechanism indicated at 3 in FIG. 1. Restoring ratchet 27 has a ratchet configuration comparable to the other ratchets 22, 23, and 24 used in the Ratchet 27 is rotated following printing in each cycle by driving engagement of drive pawl when restore magnet is energized from data source and control block 4, FIG. 1.

The restoring principles are illustrated in elementary form in FIG. 4. The mechanism in FIG. 4 comprises a cylindrical print head 81 mounted on a shaft 82. Shaft 82 freely supports a selection ratchet 83 that moves in a direction indicated by arrow 84 to rotate print head 81 for selecting a particular vertical column of characters for printing. Print head 81 has an associated drive arm 85 that is fixedly mounted to shaft 82 and that is normally maintained in a home position against a stop 86 by the action of spring 87. Pivotally mounted to the extremity of arm 85 at 88 is a drive pawl 89 that is engaged with selector ratchet 83 during selection. If selector ratchet 83 is driven in the direction indicated by arrow 84, print head 81 will be driven a corresponding amount due to the engagement of pawl 89 and the driving relation of arm with respect to print head 81. Such movement will take arm 85 in a circular clockwise path away from home position stop 86. Concurrently with rotation of print head 81 to select a particular vertical column, print head 81 may also be moved vertically to select a particular row, with the coordinate location of row and column determining the character selected for printing. Such vertical selection is indicated diagramatically in FIG. 3 at 72.

Following the selection procedure for selecting a particular character on print head 81 for printing, printing is performed by mechanisms not shown in FIG. 4. Subsequent to the printing operation, a disengaging pin 98 is moved in a direction indicated by arrow 91 to disengage drive pawl 89 from selector ratchet 83. When such disengagement occurs, spring 87 pulls arm 85 and print head 81 back to the home position stop 86. Such restoration of print head 81 occurs in a rapid and efiicient manner due to the relatively. light weight and low mass of the elements involved. When arm 85 has been repositioned to home position against stop 86, pin 90 is Withdrawn from engagement with pawl 89 thereby permitting pawl 89 to re-engage selector ratchet 83. Since print head 81 is effectively disconnected from selector ratchet 83 during the restoring portion of any print cycle, it is unnecessary to restore selector ratchet 83 to any predetermined or home position. Therefore, selector ratchet 83 merely stays in the position to which it was driven prior to disengagement of pawl 89 and upon re-engagement of pawl 89, selector ratchet 83 is immediately ready to be driven by selection members, not shown, in order to again drive print head 91 to a desired columnar position, as required.

The principles of selection and restoration of the printing mechanism just described in connection with FIG. 4 are also applicable to the printing mechanism in FIG. 1. Pawl 26 is mounted on pin 47 extending from the lower surface of print wheel 6 and when output ratchet 25 is rotated during any selection interval, print Wheel 6 is rotated at corresponding rotary amount due to the driving engagement of pawl 26 with output ratchet 25. Restore ratchet 27 has slots 27a and 27b. Pawl 26 has a pin 37 extending into an angular cutout portion of slot 27a for normal driving engagement with restore ratchet 27. Slot 27b accommodates a pin 39 extending from the lower surface of print wheel 6 having an associated spring 49 connected to a stud 50 on restore ratchet 27.

During the selection interval of each printing cycle, movement of output ratchet 25 imparts corresponding movement to print wheel 6 due to the engagement of pawl 26 With a tooth in output ratchet 25. Concurrently with the movements of ratchet 25 and print wheel 6, restore ratchet 27 is also moved due to the engagement of pin 37 with the right angle portion of slot 27a.

Following the printing of a character, magnet 45 is energized, thereby pivoting actuating element 51 against drive pawl 40 and engaging pawl 40 with restore ratchet 27. Ratchet 27 thereupon is moved in a direction indicated by arrow 46, FIG. 1. The movement of ratchet 27 disengages pawl 26 from output ratchet 25 due to engagement of pin 37 in slot 27a. As ratchet 27 is moved, stud 56 is also moved and stretches spring 49 in relation to pin 39 on print wheel 6. Subsequently, when magnet 45 is de-energized and drive pawl 40 disengaged from restore ratchet 27, the energy stored in spring 49 returns ratchet 27 to a normal relative position with respect to print wheel 6. This action enables drive pawl 26 to re-engage output ratchet 25 in preparation for the next print cycle.

Because of the unique arrangement of elements in the printing mechanism, restoration of the printing mechanism following printing in each cycle occurs in a rapid manner, as shown by the steep slopes on the restore spring line, the head rotation line, and the head vertical line in FIG. 6. Since print Wheel 6 is disengaged from the relatively heavier selection elements, spring 7 operates with high speed to restore print wheel 6 to home position in readiness for the next print cycle. Due to the configuration of the selecting elements that are generally circular in nature, no restoration action is necessary and no delay is encountered due to restoring these elements, as is usual in conventional printing mechanisms.

Selecting portion 2 of the printing mechanism shown in FIG. 1 can take forms other than that illustrated so long as the primary principle of operation is retained, that is, a progressive type of selection with the elimination of necessity for restoring the mechanism to a home position. It is conceivable that gear racks or other configurations could be modified to serve the required selecting function. A series of gear racks, for example, can be arranged, each with a large number of teeth such as the teeth on actuator discs 22, 23, and 24 wherein movement of the racks is effected during a selection interval of each cycle and the racks move generally in a particular direction during a plurality of successive cycles. The apparatus could then be arranged to restore the racks periodically after completing a large number of cycles, such as fifty or more, thereby eliminating the necessity for restoring the racks during each and every cycle.

Accordingly, while an endless type of selecting element, such as circular actuator discs 22, 23, and 24 is preferred, it is feasible to employ the principles of operation of the present invention to a wide variety of other types of mechanisms.

In line with this, reference is made to FIG. 3 wherein the mechanism of FIG. 1 is shown assembled as a compact arrangement of elements indicated with corresponding reference numerals. For simplicity, not all elements are shown. As an illustration of the type of modification to which the present invention lends itself, print wheel 6 can be replaced by a cylindrical print head such as print head 73. In this case, a splined shaft 74 is used in preference to shaft 5, FIG. 1. This enables print head 73 to be raised and lowered in order to select a particular horizontal row of characters and also permits selective rotation of print head 73 to select a particular column, with the character printed being determined by the horizontal and vertical coordinate positions in the matrix on print head 73. The mechanism of FIG. 3 includes a coil spring 75' that restores print head 73 to home position in a manner comparable to the restoration of the print wheel 6. The vertical positioning of print head 73 is accomplished by the vertical selection mechanism briefly indicated at 72. Such mechanism can take a number of forms as indicated at 95 and96, FIG. 3. The mechanism indicated at 95 is predicated on the rotary planetary gear selecting principles used in connection with the printing apparatus of FIG. 1 Such mechanism lends itself adequately to positioning print head 73 in a vertical direction as indicated by arrow 97. Means similar to restoring mechanism 3, FIG. 1, not shown in FIG. 3, can be provided :so that the progressive selection and restoration principles used in the rotary selection described in connection with FIG. 1 are applied to the vertical selection performed by mechanism 95, FIG. 3.

As another alternative, the whiffle-tree arrangement '96 can be used to position-print head 73 vertically as indicted by arrow 98, FIG. 3. The whifile-tree mechanism 96 includes a bellcrank member 99 connected to two selection magnets 100 and 101. Magnets 100 and 101 are energized in various combinations to move links 102 and 103 varying amounts and to thereby impart varying amounts of movement to bellcrank 99. The movement of bellcrank 99 in turn is reflected by a comparable vertical movement of shaft 74 due to the pivotal connection of bellcrank 99 to shaft 74 at 77. Return of shaft 74 to home position can be effected by various members such a r storing spring 93. The whifl'le-tree 8 selection principles are fully described in U.S. Patent 2,919,002 issued to L. E. Palmer, and entitled Selection Mechanism for a Single Printing Element Typewriter.

The driving pawls can also be modified to suit requirements of the equipment. One possible variation of the drive pawls is shown in FIG. 5 where two pawls. 112 and 113 are arranged for driving action by cams 104 and 105 mounted on a shaft 106. Pawls 112 .and 113 are arranged to drive selection ratchets 107 and 108 as indicated by arrows 109 and 110, respectively. Ratchets 107 and 108 are driven in opposite directions in a manner comparable to the driving of ratchets 22 and 23, FIG. 1.

Numerous modifications can be made to the inventive arrangements disclosed herein depending upon the requirements of the application involved. For example, while the total aggregate motion of output ratchet 25 in FIG. 1 was indicated as being derived from the individual weighted motions of the actuator cams 22, 23, and 24, it may be desirable under certain circumstances to have the output motion of output ratchet 25 be a net motion representing movements of the selector elements in both positive and negative directions. The selector arrangement of FIG. 5 lends itself to such an arrangement. As an example, movement of ratchet 107 in a clockwise direction indicated by arrow 109 may impart clockwise movement to a print head driving member attached to shaft 111. On the other hand, movement'of ratchet 168 in a counterclockwise direction indicated by arrow 110 may result in a corresponding counterclockwise movement of the print head driving member attached to shaft 111. Under such conditions, the net movement imparted to the print head would depend upon the net movement resulting from the combined clockwise rotation of selector disc 107 and the counterclockwise movement of selector disc 108. As one example, the mechanism of FIG. 5 may be arranged so that movement of selector disc 107 five units in a clockwise direction and movement of selector disc 108 one unit in a counterclockwise direction results in a net movement of four units of the print head driving element in a clockwise direction. The foregoing illustrates the fact that the selector elements may all move in the same direction, opposite directions, or combinations of directions, as desired. t

While the printing mechanism has been illustrated in connection with printing of mathematical symbols, the principles are equally applicable to the printing of any characters including numeric or alphabetic as well as other special characters, such as the mathematical symbols. Also, the output of the selector portion 2 of the mechanism in FIG. 1 can be further expanded to eifect selection of characters positioned completely around the periphery of print wheel 6 rather than through a selecting are as previously described. In the case of alphabetic characters, zone selection principles can be applied to select characters according to their location in particular quadrants or sectors of print wheel 6. In that event, the ultimate character selected would be determined by a combined zone, quadrant, or sector selection in connection with a further selection within the particular zone, quadrant, or sector on print wheel 6. The same principles can be extended to cylindrical print heads 73 an 81 in FIGS. 3 and 4.

While the invention has been particularly shown and described with reference to several embodiments, it will be understood by those skilled in the art that various changes in form and detail other than those described may be made without departing from the spirit and scope of the invention.

What is claimed is: g

1. Cyclically operable printing apparatus, comprising:

a printing member, said printing member having a plurality of embossed characters thereon, and mounted for selective movement from a home position relative to a printing station in order to position one of said characters for printing;

actuatable selector means progressively movable in a preferred direction, said selector means including rality of embossed characters thereon, and mounted for selective movement a corresponding plurality of particular distances during each cycle from a home position relative to a printing station in order to planetary gear members, each of said gear members position any one of said characters for printing; having teeth formed in its periphery, the pitch of actuatable non-restore home selector means progresthe teeth formation corresponding to increments of sively movable always in a preferred direction: movement of each of said gear members; means normally interconnecting said selector means to means normally interconnecting said selector means to said printing member in order to move said printing said printing member in order to move said printing member as said selector means is moved; I member as said selector means is moved; control means operable in each cycle for selectively coded control means for selectively actuating said seactuating said selector means a particular predeterlector means to thereby move said printing member mined distance only in said preferred direction to in order to position a particular character on said thereby move said printing member in order to printing member for printing, said coded control position a particular character on said printing memmeans having a rotatable shaft, pawl means mounted her for printing; for movement on said shaft and for selective engageprinting means operable during each printing cycle ment with said gear members, and electromagnetic following selection of a character to print the selected means associated with each of said pawl means for character on a document; selectively engaging the same in response to coded normally ineffective means for restoring said printing impulses; member to said home position; printing means operable during each printing cycle and means operable following printing in each cycle following selection of a character to print the selected to disconnect said printing member from said selector character on a document; means in order to thereby render said restoring normally ineffective means for restoring said printing means effective to return said printing member to member to said home position; said home position and to also retain said selector and means operable following printing in each cycle means in the position reached during the cycle just to disconnect said printing member from said selector Completed n in mm at r din ss f r a t ati n means in order to thereby render said restoring means to Select a Character in a IleXi Succeeding y effective. 6. The apparatus of claim 5, wherein: 2. The apparatus of claim 1, wherein: said selector means comprises a planetary gear arrangeisaid printing member comprises a cylindrical print head m rit having a plurality of actuator gear members having a matrix arrangement of characters with each always moved in a preferred direction, each of said character selected by reference to a vertical and gear members being controlled by said control means horizontal coordinate matrix location, and wherein and each of Said g members selectively contributsaid actuatable selector means is operable to move ing a weighted movement portion to the required outsaid cylindrical print head for selecting a particular p movement required to position said printing character in relation to a particular one of said member. coordinate matrix directions, and wherein 7. The apparatus of claim 5, wherein: additional actuatable selector means is provided for said printing member comprises a cylindrical print head moving aid print head in the e ond on of aid having a matrix arrangement of characters with each coordinate directions in order to thereby select a character selected by reference to a vertical and horiparticular character for printing, said additional se- ZOIltal coordinate matrix location, a d Wh n lector means including a whiflle-tree mechanical said actuatable selector means is operable to move said arrangement responsive to coded controls for posicylindrical print head for selecting a particular chartioning said cylindrical member in the required secacter in relation to a particular one of said coordinate 0nd coordinate direction. matrix directions, and wherein 3. The apparatus of claim 1 wherein: additional actuatable selector means is provided for the output of said selector means is imparted to said moving said print head in the second one of said coprinting member by a circular output ratchet, and ordinate directions in order to thereby select a parwherein ticular character for printing. said printing member is interconnected with said out- 8, The apparatus f l i 7 h i put ratched by a drive pawl, and wherein said additional actuatable selector means is also prosaid restoring means comprises a circular ratchet memgressively movable only in a preferred direction.

her having a slotted portion engageable withsaid drive pawl, and wherein said restoring means fur- References Cited by the Examiner ther comprises meakris sellectively operable following UNITED STATES PATENTS printing during eac cyc e to operate said restoring ratchet and thereby disengage said drive pawl by 738362 9/1903 Wall 235 144 the cooperative action of said slot-ted portion with 910806 1/1909 Falvey 235' 144 X Said drive paWL 1,048,605 12/1912 Trickle 235-144 X 4. The apparatus of claim 3 wherein: 2144176 1/1939 Amann 178 34X resilient means is interconnected between said printing 2,358,477 9/1944 Salmon 178 34 member and said restoring ratchet to restore the 3,029,921 4/1962 Reynard initial relationship of said restoring ratchet with re- 3069083 12/1962 Haydon 235*144 X spect to said printing member and to thereby permit 32241545 12/1965 Han-ft re-engagement of said drive pawl with said out ut ratchet in preparation for a subsequent printing cy le. ROBERT PULFREY Primary 5. A cyclically operable printing apparatus, compris- 7 E. S. BURR, Assistant Examiner. mg:

a printing member, said printing member having a plu- 

1. CYCLICALLY OPERABLE PRINTING APPARATUS, COMPRISING: A PRINTING MEMBER, SAID PRINTING MEMBER HAVING A PLURALITY OF EMBOSSED CHARACTERS THEREON, AND MOUNTED FOR SELECTIVE MOVEMENT FROM A HOME POSITION RELATIVE TO A PRINTING STATION IN ORDER TO POSITION ONE OF SAID CHARACTERS FOR PRINTING; ACTUATABLE SELECTOR MEANS PROGRESSIVELY MOVABLE IN A PREFERRED DIRECTION, SAID SELECTOR MEANS INCLUDING PLANETARY GEAR MEMBERS, EACH OF SAID GEAR MEMBERS HAVING TEETH FORMED IN ITS PERIPHERY, THE PITCH OF THE TEETH FORMATION CORRESPONDING TO INCREMENTS OF MOVEMENT OF EACH OF SAID GEAR MEMBERS; MEANS NORMALLY INTERCONNECTING SAID SELECTOR MEANS TO SAID PRINTING MEMBER IN ORDER TO MOVE SAID PRINTING MEMBER AS SAID SELECTOR MEANS IS MOVED; CODED CONTROL MEANS FOR SELECTIVELY ACTUATING SAID SELECTOR MEANS TO THEREBY MOVE SAID PRINTING MEMBER IN ORDER TO POSITION A PARTICULAR CHARACTER ON SAID PRINTING MEMBER FOR PRINTING, SAID CODED CONTROL MEANS HAVING A ROTATABLE SHAFT, PAWL MEANS MOUNTED FOR MOVEMENT ON SAID SHAFT AND FOR SELECTIVE ENGAGEMENT WITH SAID GEAR MEMBERS, AND ELECTROMAGNETIC MEANS ASSOCIATED WITH EACH OF SAID PAWL MEANS FOR SELECTIVELY ENGAGING THE SAME IN RESPONSE TO CODED IMPULSES; PRINTING MEANS OPERABLE DURING EACH PRINTING CYCLE FOLLOWING SELECTION OF A CHARACTER TO PRINT THE SELECTED CHARACTER ON A DOCUMENT; NORMALLY INEFFECTIVE MEANS FOR RESTORING SAID PRINTING MEMBER TO SAID HOME POSITION; AND MEANS OPERABLE FOLLOWING PRINTING IN EACH CYCLE TO DISCONNECT SAID PRINTING MEMBER FROM SAID SELECTOR MEANS IN ORDER TO THEREBY RENDER SAID RESTORING MEANS EFFECTIVE. 